Posted by: @davidalgarve

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I am operating my Mitsu ASHP with Weather Compensation and I am puzzled why my Melcloud app shows a Room Temperature of around 20-21C, but I don't have any connected room thermostat device and the FTC5 is outside in the pump room where this temperature would not occur in Winter

Could anyone advise where this reading originates and will it be attempting any kind of control? 

Are you familiar with the system? It depends how the room sensor setting is set up. This is on the menu under Initial Settings (the little cog wheel). If it's set to  "Main RC" it should read the temperature from wherever the wired in controller for the FTC5 is (it's inside).  If you have a remote thermistor, which is a wired in (to the FTC) remote temperature sensor , it will read the temperature from wherever that is if the room sensor setting is set to "TH1".  If you're on WC it won't make any difference to the flow temp or house temp however it's set or whatever it reads. 

Thanks for your response Kev M.

I am becoming more familiar with the system and I am reasonably optimistic, heading into winter, that I have a much better set up than was done by the contractor at this time last year. However, this is one area where I have not understood what I have, before going on to make changes. Background is that I have an upside down house with radiators mostly fitted with TRV's (legacy of previous gas boiler set up) and a PUHZ-SW120YHA feeding a buffer tank or into a DHW tank

The room setting is on "Main RC" but there is no external wired temperature measurement device. If I understand you correctly, in that case the measurement would come from inside the FTC5, but I am sure that the FTC5 mounted on the Hydrobox in the pool pump room  is not at a temperature of circa 20C with an OAT of 11C.

I am trying to optimise for weather compensation and not a specific room or zone and I understand the options are: TH1/ MainRC/Room RC1-8/Time Zone. 

So what would a sensible setting be for Room Sensor? 

Posted by: @davidalgarve

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Thanks for your response Kev M.

I am becoming more familiar with the system and I am reasonably optimistic, heading into winter, that I have a much better set up than was done by the contractor at this time last year. However, this is one area where I have not understood what I have, before going on to make changes. Background is that I have an upside down house with radiators mostly fitted with TRV's (legacy of previous gas boiler set up) and a PUHZ-SW120YHA feeding a buffer tank or into a DHW tank

The room setting is on "Main RC" but there is no external wired temperature measurement device. If I understand you correctly, in that case the measurement would come from inside the FTC5, but I am sure that the FTC5 mounted on the Hydrobox in the pool pump room  is not at a temperature of circa 20C with an OAT of 11C.

I am trying to optimise for weather compensation and not a specific room or zone and I understand the options are: TH1/ MainRC/Room RC1-8/Time Zone. 

So what would a sensible setting be for Room Sensor? 

The room temp sensor isn't inside the FTC but inside the little control panel.  This comes with a long cable so doesn't have to be beside or near the FTC itself.The room temp is displayed on the control panel beside the little house symbol with a thermometer inside.  What does that say? 

I think Main RC is the setting you want

Perhaps I didn't make myself clear in that the room temperature figure that I was referring to is on the Melcloud app. It does not appear on the FTC5. 

There is no House symbol on the FTC5 - only the DHW temp

There is only one cable from the FTC5 and that terminates on the main panel at terminal CN22BU

See photos

Posted by: @davidalgarve

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Perhaps I didn't make myself clear in that the room temperature figure that I was referring to is on the Melcloud app. It does not appear on the FTC5. 

There is no House symbol on the FTC5 - only the DHW temp

There is only one cable from the FTC5 and that terminates on the main panel at terminal CN22BU

See photos

 

No you did make yourself clear, it was me! Apologies, the little house symbol isn't there when on WC.  If you switch to room temp control on the main panel what does it say?  Is it there and is it the same as Melcloud?  But again, on WC it isn't used for anything, which I suppose is why it's not there.

No Problem! The House symbol does not appear on any of the 3 options on the FC 5. I have just tried the other two options and then refreshed MelCloud and the Room Temperature was the same on all 3 i.e. 19C. That is as low as I have seen it but does not match ambient at 13C or living room at 21C. I did wonder if it could pick up a wireless signal from a Mitsu AC unit in that room, but that is saying room temp of 20C. These are small differences now but will increase as ambient drops in evening.

this is what kev is referring to it only appears in auto adapt mode and it’s getting the values from the remote controller thermistor.  As Kev said in WC mode they don’t do anything.  You can see in my MELCloud shot the room temp and set temp match

Sorry for being so dense, but I still do not understand. Where is the "remote controller thermistor" because I don't have a remote controller. Also, why is MelCloud picking up a temperature and the FTC5 not doing so. I can't see what in my house, could be forwarding a temperature of 19C right now. 

The FTC5 is the big metal box with ecodan on the front the remote ftc5 controller is the screen you are looking at.  The thermistor is inside the controller with the screen and will measure the temp of where ever it is located and that is the temp you are seeing in melcloud

Obviously I am completely misunderstanding because I thought that the FTC5 was the controller that is mounted on the front of my Hydrobox EHSC-VM2D and my Hydrobox is effectively outside in a pool pump room.

Admittedly the whole Hydrobox will gain some heat, but it seems strange that it consistently outputs close to 20C when the ambient goes down to 8-9C.

Also, could you explain why this always give a temperature on the MelCloud, but not on the control panel, using any of the 3 configuration options?

@davidalgarve  I don’t have a hydro box so your system is different to mine.  I wouldn’t worry about it if you are using WC it doesn’t use those values anyway.